Yieldable gear.



No. 807,692. PATENTED DBO. 19, 1905. H. B. STILZ. YIELDABLE GEAR.

APPLICATION FILED JAN.14. 1905.

" V//l/A Il gles to Fig. 2.

HARRY B. STILZ, OF PHILADELPHIA, PENNSYLVANIA.

YIELDABLE GEAR.

Application lerl January 14, 1905. ISerial No. 241,089.

To @ZZ whom, t may concern.-

Beit known that l, HARRY B. STILZ, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Yieldable Gear, of which the following is a specification.

My invention relates to improvements in yieldable gears used in transmitting power through shafting in which the speed of one shaft ma)v1 be varied without interfering with the operation of the other shaft; and the objects of my improvement are, first, to provide an arrangement in which a large torque can be obtained between the frictional surfaces with a comparatively small friction-producing force; second, to bring the frictional surfaces into action in such a way that no longitudinal thrust is necessary to maintain the friction-producing force, and, third, to com bine the various parts so as to make the arrangement compact and simple. I attain these objects by the mechanism illustrated in the accompanying drawings, in which* Figure 1 is an elevation and part section of the gear and mechanism assembled on a plane at right angles to the shaft. Fig. 2 is a half-section of the gear on a plane through the axis, cutting the key between the ends of the band. Fig. 3 is a half-section at right an- Fig. 4 is an elevation of a small part of the wheel A. Fig. 4a is a plan view of Fig. 4, and Fig. 5 is a diagrammatic view 0f the resolution of forces.

The wheel A is provided with a slot around its periphery of size sufficient to permit the friction-band B to be placed therein and contracted into a circumference not greater than the greatest circumference of the wheel, so that the gear C can be slipped over the band to its position on the wheel. The band is then expanded into the corresponding slot provided on the inner circumference of the gear, and the key lc, positioned between the ends of the band, is inserted into a keyway, so tapered as to prevent its slipping out radially, and fastened longitudinally by the screw a. The band B is provided with shoulders near its ends on which the thrust from the togglejoint D is taken.

one end and connected at the other to a mechanism which brings into action the pressure from the spring G, is slotted in the vicinity of its middle to hold the toggle-joint in position.

The principle on which the gear operates Specification of Letters Patent.

The lever E, pivoted at Patented Dec. 19, 1905.

depends on the formula frictional surfaces and Y the angle iifdegre'es.

through which this friction acts. P, P2 will be the pressure exerted by the band on the v key 7c, which when multiplied by the outside radius of the friction-band will Agive the torque at which the gear will yield. ,With the gear turning in either direction the resolved pressure from the spring will be such as is required by the slack end of the band only, the key lc taking all the thrust due to the turning moment on the gear.

In Fig. 5 let Y be the line of action of the force from the spring on the end of the lever,V the line of force on the other end of the lever, this being supported by the pivot, and X the line of force on the toggle. Assuming a force of two hundred pounds being exerted by the spring at Y, then since the length of the power-arm of the lever shown is to the length of its weight-arm .as thirteen is to six, we have the force acting on the toggle in line with X equal to y pounds... The lines PX in the diagram being drawn parallel to the lines of force in the arms of the toggle represent the amount and direction of the forces therein. Then twice the line OX will represent the force from the lever. Each force PX has a component tangential to the band represented by OP,which components represent the forces tending to separate the ends of the band. The force acting in line with OP will therefore be, to the force received from the lever, as OP is to twice OX, and with the toggle in the position shown this force is equal to pounds. Assuming a coefficient of 0.2 and considering a=345 degrees, we have IOO IIO

pounds, which force Would befeXerted on key k When the gear yields, provided only tangential forces Were received from the mechanism. With the mechanism shown radial forces are in action. These modify the pressure on the key 7c by additions which need not, however, be considered in practice, being comparatively small in their effect.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The combination of a shaft, a Wheel secured to the shaft, a gear concentric With and rotatable relative to the shaft and having a friction-surface, a split band loosely fitted around the circumference of the Wheel, a key secured td'the' Wheel 'in a position to react upon the thrust end of the band, and a mechanism by Which a force is applied to the slack and said Wheel, and a mechanism by Which the band is actuated against the gear.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

HARRY B. STILZ.

Vitnesses BENJAMIN R. WOOD, S. SHEA COMMENTZ. 

